Field of the Invention
The present invention relates to an image forming apparatus, a method of controlling the same and a storage medium.
Description of the Related Art
Because the time period that an image forming apparatus is in a standby state is very much longer than an operation time period, demand for power conservation when the image forming apparatus is in the standby state has been growing. In response to this kind of demand, a power conservation mode for waiting with less electric power consumption than the electric power consumption upon standby of a normal mode has been realized in conventional image forming apparatuses. In a power conservation mode, a power-supply to portions other than a control unit, such as a printer unit, a reading unit, or the like, for which the power-supply is unnecessary in standby is stopped. Furthermore, in order to reduce electric power consumption, for example, Japanese Patent Laid-Open No. 2002-268473 proposes a technique for dividing a power-supply circuit of a device into a plurality of power-supply circuits, and controlling power-supply to each electric circuit from each of the power-supply circuits.
However, in the above described conventional technique, in the control module for controlling the power-supply, the generation of a high-power-supply voltage such as 38V, or 24V is stopped when an operation of a scanner, or the like, is completed, and when a copy operation is instructed, instruction is made to each power-supply circuit so as to generate the high-power-supply voltage. Here, after the control module instructs so as to generate the high-power-supply voltage, or to stop, transition is made into control of a motor, or the like, but a time difference occurs between the time when the high-power-supply voltage is generated or stopped and further circuit control voltage is generated from that high-power-supply voltage, and the operation of the electric circuit that is supplied with power. For this reason, there were cases where the control module outputs a signal for driving the circuit of the drive unit even in a case where after generation of high-power-supply voltage is instructed, voltage of the drive unit is not generated yet and it so cannot operate, and there was the problem that integrity was decreased.